Method of making elastic fluid turbines



Patented Sept. 26, 1939 METHOD OF MAKING ELASTIC FLUID TURBINES John H. Doran, Scotia,

N. Y., assignor to General Electric Company, a corporation of New Yori; Application April 1, 193s, semi No. 199,466

4 Claims.

The present invention relates to elastic fluid turbines, more specifically to methods of making welded turbine rotors.

The general object of my invention is to provide an improved method of making welded turbine rotors whereby stresses in the shaft portion of such rotor are reducedto a minimum.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in, connection with the accompanying drawing.

In the drawing, Figs. 1 and 2 illustrate an elas tic fluid turbine rotor in different stages of manufacture in accordance with my invention and Fig. 3 shows a modification of my invention.

The finished rotor as shown in Fig. 2 comprises a shaft I0 with a plurality of bucket wheel disks II secured thereto by welds I2. The shaft portions intermediate the disks are machined to form packing grooves I3. The diameter I4 of the shaft proper is smaller than the smallest diameter I5 of the welds I2` This is an important feature of my invention because the shaft proper with the diameter. I4 is thereby kept free from stresses set up during the manufacture of the welds I2. The welds I2 actually are formed between annular projections or collars I6 of the shaft and the adjacent surfaces of the bucket Wheel disks II. If any stresses are set up during the welding operation, such stresses are set up in the projections or collars I6, that is, outside the shaft proper with the diameter I4. 'I'he rim of each disk is machined to receive bucket blades (not shown).

During manufacture of such welded rotor structure I form a shaft III, as shown in Fig. l, with a plurality of axially spaced projections or auxiliary collars I1. This shaft is assembled with unfinished disks II each having inner annular projections I8 on one side engaging'the aforementioned projections I 1. The adjacent surfaces of the disks I I and the shaft I0 form large grooves I9 which subsequently are material 20. The projections I1 and I8 serve as centering surfaces for the disks I I and at the same time as backing for the welding material 20. AAfter the disks II have thus been welded to the shaft III, the structure is machined, that is, the shaft intermediate the adjacent disks is provided wth packing grooves I3, shown in Fig. 2, and the surfaces of the disks and the end portions of the weld, as well as the projections I8, I1, are removed to assure a connection between the shaft and the disk.

filled with welding perfectly sound welding' (Ci. Ztl-156.8)

The modification of my invention, as shown in Fig. 3, comprises a shaft which hasa collar 26 with a projection 21 forming a shoulder 28 at one end of the collar. The outer surface of the collar is considerably radially spaced from the surface of the shaft, that is, from the shaft proper, the diameter of the collar 26 being preferably about two inches longer than the di-A ameter of the shaft 25. During manufacture the shoulder 28 on the collar is engaged bya disk 29 which forms a bore 30 and has a wall portion 3l on one side of the bore projecting radially irlward and at the same time laterally outward, that is, away from the disk. This wall portion or projection 3i engages the shoulder 28. The groove formed between the bore of the disk and the outer surface of the collar 26 is filled with welding' material 32. After the disks and the shaft have thus been welded together, the structure is machined into its final shape, similar to that shown in Fig. 2.

The method and arrangement illustrated in Fig. 3 permit the use of thinner disks and also assures a more certain weld because the first layer of welding material is laid against the thin wall portion 3i.

The rst layer of welding material is the most difficult one to make on any Welded joint. Much depends upon it because if a crack should start it must be cut out before any more weld can be laid in. The first layer also shrinks more than subsequent layers. It therefore tends to pull the two surfaces being joined together more than a subsequent layer, and consequently special precaution must be taken to make the metal surfaces being joined in such a way that the shrinkage can take place with a minimum stress. This is accomplished in the arrangement of Fig. 3 because the long thin projecting wall portion 3I bends very easily.

What I claim as new and desire to Letters Patent of the United States is:

l. The method of making a welded turbine rotor comprising forming a shaft with a plurality of axially spaced annular projections, assembling with the shaft a plurality of disks each having an annular projection centered on a projection of the shaft and formingl a large groove with the shaft, filling the grooves with Welding material, and removing at least one of the projections and some of the welding material near said projections. n

2. The method of making a Welded turbine rotor comprising forming a shaft with a plurality of axially spaced annular projections; assembling secure by lill with the sliait a plurality oi disks having ao. annular projection centered om a projection oi the shait and forming a large groove with time shaft, lling tire grooves with Welding material, machilling the sides of the disks to an extent that the projections oi the disk and the shaft are removed.

3. 'Mie method vof making a Welclecl turbine rotor comprising forming a shaft with a plurality of intermediate axially spaced annular projet:n tions, assembling with the shaft a plurality of disks each forming a groove with the shaft and having an annular projection centered on a projection oi the shaft, filling the grooves with Weldi-s ing material, and machining the shaft interinale cliate adjacent disks so the diameter of the awaeso shaft intermediate the disks is smaller than the smallest diameter of tile Welded portions.

4. The method of making a welezleol turbine rotor comprising forming a shaft with a. coliar having a projection forming a shoulder, assem-v oling with the shaft a clisk having a bore with a Wall portion at one end. thereof projecting radially inward and laterally outward with the end of the portion seated against said shoulder, the bore and the outer surface of the collar forming a large groove, lling the groove with Welding material, and machining away the projecting' Wall `portion.

JDHN l-. ECRAN. 

